Oki Electric Industry Co., Ltd.

Ichiji Yamamoto

Toshiyuki Iwabuchi

Kazuo Nakano

A thermal recording system in which a thermal treated paper is printed by a thermal head having a series of aligned heat-generating resistor elements and current-holding elements like SCR (thyristor) corresponding to each of said heat-generating resistor elements for holding electric current. The power source for heating said resistor elements is a periodic voltage like a commercial alternate current (A.C.), or a pulsating current which is obtained by rectifying the commercial alternate current. The printing to each cell is accomplished within a single period of said periodic power source, and the duration of heating the resistor elements within said single period is controlled according to the peak voltage or current of the power source, in order to provide the constant concentration or density of printing. Thus, means for converting the peak value of the power source to the time delay is provided. The resistor elements are heated after said time delay in each half cycle of said periodic power source, until the instantaneous voltage or current of the power source reaches zero. Then, the printing concentration is free from the change of the voltage of the power source.

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Tokyo, Japan

Ichiji Yamamoto